How does a neurosurgeon know if their treatments work? What role does this play in how the mind of the neurosurgeon makes patient care decisions?
An essential part of academic medicine has always been the critical evaluation of patient outcomes. Without this, it is impossible to understand whether a (surgical) treatment was beneficial for a patient. How outcome is measured, however, has changed considerably several times over the last decades.
In the Beginning
Individual case reports were the first reports of outcome, consisting of extensive narratives (often more than 100 pages) and often containing beautiful illustrations of longitudinal outcome with abundant detail. Such reports were impractical for generalization to the broader population of neurosurgical patients or to derive therapeutic evidence. However, case series followed, which often included some kind of categorical physician-rated outcome. Scales were not standardized, usually very basic (e.g., better/same/worse) and fully dependent on the physician’s subjective impression of the patient’s well being. Even today, physician-rated outcome scales remain the gold standard for diseases and conditions, where patients may not be able to self-evaluate their condition because of reduced vigilance, (severe) neurological deficiency or neuropsychological impairment. After aneurysmal subarachnoid hemorrhage, for example, the three most highly-recommended outcome measures as defined by the NIH/NINDS common data elements group are the physician-rated modified Rankin Scale (mRS) or the Glasgow Outcome Scale (GOS) and the screening of neuropsychological functions (Montreal Cognitive Assessment).1 Such outcome assessments are best performed by a qualified physician, who has received formal training and certification. Independent outcome assessment by a physician not directly involved in the treatment additionally reduces the risk of biased grading. While this may be impractical for daily patient care, it is of particular importance for clinical research.
A New Era: Patient-Reported Outcome Measures
The impression of treatment success/failure of patients and their surgeons can diverge. Thus, modern and increasingly patient-centered health care was a driver of Patient-Reported Outcome Measures (PROMs), consisting of subjective and typically questionnaire-based generic or disease-specific patient self-assessments. An application par excellence for PROMs is spine care – where the description of outcome is complex and has to account for many dimensions. Accordingly, different PROMs have been proposed, ranging from simple single-item scales, such as the Visual Analog Scale (VAS) for pain to multi-dimensional assessments of disability (e.g., Oswestry Disability Index), satisfaction, health-related quality of life (hrQoL; e.g., Short-Form (SF)-36, Euro-Qol (EQ-5D)) and many others. Most of the frequently applied PROMs have been studied thoroughly and their reliability, validity, objectivity and responsiveness have been demonstrated. Some of them are standardized, meaning that the raw scores of healthy persons of the normal population are known, and the degree of a patient’s suffering can be determined by calculating the patient’s deviation from normal. Furthermore, by means of the Minimum Clinically-Important Difference (MCID) of a PROM – a threshold that indicates improvement/worsening on an outcome measure that is noticed by the patient as clinically relevant – the real impact of a health care intervention on the subjective well-being can be determined. Those important developments have set the grounds for the concepts of value-based medicine, comparative effectives analyses and more.
Are PROMs the End of the Line?
PROMs are criticized for their very subjective character, which makes them prone to fluctuations and bias from the emotional state of a patient. Patients with degenerative diseases of the spine that also suffer from depression, for example, are known to rate their pain, disability and hrQoL as worse when compared with patients without depressive comorbidity.2 Additionally, educational, cultural and motivational variety influence PROM-based rating. Furthermore, some of the items of PROM questionnaires (e.g., questions about travelling, sex life, etc.) may not apply to all patients or be misunderstood. Often, PROMs for spinal diseases center on pain, but there are patients that do not seek advice for pain, but for progressive loss of (motor) function.3
Consequently, research in the last couple decades has worked on establishing objective methods of outcome assessment, e.g. simple, typically timed functional assessments, such as the Timed-Up and Go (TUG) or the 5-Repetition Sit-To-Stand (5R-STS) test.4-6 The broad application of smartphone technology has opened additional venues for outcome assessment in neurosurgery. By tracking global-positioning system (GPS) coordinates, a patient’s mobility can be determined before and after neurosurgical procedures.7 Moreover, a patient’s frequent interactions with the smartphone touchscreen reflects activity that can be used for unobtrusive and longitudinal big-data analyses. Such analysis could detect change in cognitive function or complications related to cranial procedures.
We can conclude that describing the health status or outcome of our patients is complex, since for each neurosurgical disorder, many aspects must be accounted for. Moreover, the impressions of the patient and the physician are not necessarily synchronous. Whenever possible, subjective outcome measures should be obtained from both the patient and care provider. If both point in the same direction (either positive or negative), the physician can be confident that the result represents the truth. This is less certain if the patient- and physician-based ratings diverge. Objective measures could then be employed to add a further dimension of outcome that is less prone to bias.6 Considering technological advances, the role of objective and unobtrusive outcome measures in assessing treatment success/failure will likely increase further in the near future and eventually render pencil and paper PROM questionnaires unnecessary.
1. Akeret, K., Vasella, F., Geisseler, O., Dannecker, N., Ghosh, A., Brugger, P., … Stienen, M. N. (2018). Time to be “smart”—Opportunities Arising From Smartphone-Based Behavioral Analysis in Daily Patient Care. Frontiers in Behavioral Neuroscience, 12.
2. Bostelmann, R., Schneller, S., Cornelius, J. F., Steiger, H. J., & Fischer, I. (2015). A new possibility to assess the perioperative walking capacity using a global positioning system in neurosurgical spine patients: a feasibility study. European Spine Journal, 25(3), 963–968.
3. NeuroPoint Alliance. (2018). QOD Spine Registries. https://www.neuropoint.org/registries/qod-spine/
4. Gautschi, O. P., Smoll, N. R., Corniola, M. V., Joswig, H., Chau, I., Hildebrandt, G., … Stienen, M. N. (2016). Validity and Reliability of a Measurement of Objective Functional Impairment in Lumbar Degenerative Disc Disease. Neurosurgery, 79(2), 270–278.
5. NIH/NINDS, J. (2017). Unruptured Cerebral Aneurysms and Subarachnoid Hemorrhage | NINDS Common Data Elements. Retrieved from https://www.commondataelements.ninds.nih.gov/Unruptured%20Cerebral%20Aneurysms%20and%20Subarachnoid%20Hemorrhage
6. Staartjes, V. E., & Schröder, M. L. (2018). The five-repetition sit-to-stand test: evaluation of a simple and objective tool for the assessment of degenerative pathologies of the lumbar spine. Journal of Neurosurgery: Spine, 29(4), 380–387.
7. Stienen, M. N., Smoll, N. R., Joswig, H., Snagowski, J., Corniola, M. V., Schaller, K., … Gautschi, O. P. (2017). Influence of the mental health status on a new measure of objective functional impairment in lumbar degenerative disc disease. The Spine Journal, 17(6), 807–813.
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